Production of solid finely-divided material



May 15, 192s; 1,670,049-

L. scHER-r'sl. E1' AL' PRODUCTION 0F SOLID FINELY DIVIDED MATERIAL FiledNov. 14. 1922 Y. fasi-sam j 22 @my Fig. 3. (ANB Inventrs:

Patented May l5, 1928.

UNITED STA res . LUDWIG SCHEBTEL ANI)A WILLI ITY, lF ESSEN, GERMANY,ASSIGNORS TO THE FIRE TH. GOLDSCHMIDT A.G., OF ESSEN, GERMANY.

IRODCTION 0F SOLID FINELY-DI'VIDED MATERIAL.

Application led November 14, 1922, Serial No. 600,882, and `in GermanyNovember 15, 1921.

This invention relates to the production of solid finely dividedmaterial, such as lead oxid, suitable for compositions, and varioussimilar uses.

In a general aspect the invention consists in the provision of a processwherein raw material, such, for example, as molten metallic lead'orpulverulent lead oxid, is distributed over and permitted to-vaporze l0from surfaces of an inert refractory material which is heated to atemperature of the order of 1000 degrees C.; and at the same time hotgases or products of combustion are permitted to flow over the surfacesthereby causing the formation of a fume of lead oxid which is removedfrom the region of the hot surfaces and collected in a suitable mannerto obtain a high yield of material in a state of extreme sub-division.

If molten lead be employed as thef-raw. materialthe hot gases are of anoxidizing nature in order to convert the metal vapors to oxid. If leadoXid be employed as a raw material the hot gases may be products ofcombustion. In either event a relatively 'large volume of gas isemployed to effect the formation of a fume which is highly'`dispersed'through the gaseous medium, and to obtain a high proportion ofnely divided material with a proportionate decrease in thev amount ofcoarser particles. Coarse particles contained in the eflluent mixture ofgases and fume are permitted to settle out under the influence ofgravity and the cleaned fume is then collected or precipifated by asuitable means such as an electrical discharge.

In the accom anying drawing; Fig. 1 is sc ematiclongitudinalcrosssectional view of an apparatus for practic-v ing our invention.

Fig. 2 isl a schematic longitudinal crossjf. sectional viewf anothertype of apparatus,; and

Fig. 3 is a transverse cross-sectional view taken along the line A--B ofFig. 2.

Referring to Fig. 1, there is illustrated a tower 1 of refractorymaterial, in whlch 1s disposed a stack of refractory bricks, 2, whichare slightly spaced from each other and provide a large surface area,and which are so arranged as to permit the passage of hot gases betweenthel bricks. An inlet port 3, formed at the bottom of the tower 1, visprovided for the admission 0f hot gases from a suitable source, notshown. The upper end 1a of thev tower is ,of somewhat largercross-sectional area than the base thereof to effect a decrease invelocity of the gases prior to their emergence from the tower.Positionedabove the tower isa receptacle or hopper 4 in which isdisposed a quantity 4a of raw material such as molten metallic. lead orlead oxid.

The hopper 4 is provided with a port 5 opening into the tower 1 abovethe stack of bricks 2, which may be opened or closed by manipulating avalve 6. An exit port 7 is provided at the upper end of the tower 1, andto itis attached a pipe line 7n which terminates in an electricalprecipitating apparatus 8. The framework of the member 8 is connected toone pole of a. generator 9, or other source of electricalenergy, theother pole of which is connected toA electrodes 10 disposed within thechamber 8. Under the influence of the electrical discharge, fume carriedinto the chamber 8 from the tower 1 is precipitated, andthe conveyinggases are permitted to escape through a port 11. The precipitatedmaterial collects in a receptacle 12 disposed be- 'low the chamber 8 andmay be removed therefrom through a gate 13.

The apparatus shown in Fig. 2 comprises a. shell 20 having a lining ofrefractory material and an inlet port 21 for, the admission of hotgases. A rotatable shaft 22, extending through lthe shell 20 is providedwith a v bore to permit of water cooling, and has mounted thereon atintervals a pluralityof perforated discs 23, consisting of, or coveredwith, 'refractory material. The shell. 20,is adapted to receive aquantity of molten material 24. The discs .23 rotate within the bath 24,and carry above it thin films of raw material which is vaporized,converted to a fume by gases entering through the pipe 2l, and removedto a suitable settling and precipitating apparatus through an exit port25.

In both types of ap ar'atus there -is provided an extensive sur ace areaupon which the raw material may be distributed and from which itisvaporized .and converted to a fume.

Referring again to Fig. 1, in operation, the-tower and containedbrick-work 2 are brought to -a suitable temperature. (about 1000 C.) and.molten material, y,such as lead,

'nsl

i's allowed to trickle through the port 5, fall as aspray, anddistribute itself as a thin film over the brick-Work. Here it isvaporized into the surrounding atmosphere and converted into a fume heldin suspeiision by the large .volume of hot,- gases entering through theport 3. Coarse particles of marefractory surfaces of large area.owinging volatilization, excessive temperaturesneed not be employed, anda high yield of finished material is obtained.

It is apparent that the principles ofthe` invention may be applied withvarious types of apparatus, and that the operating conditions indicatedabove may be varied to meet the necessities of any case. Thus, the`rocess is applicable to the formation of ely divided antimony or tincompounds, which we regard as equivalent to plumbiferous substances. Inmakina` antimony trioxid, for

example, the cylinder 20 is partially filled with molten antimonymonoxid, or if desired, With molten antimong, in which case' ustion areusedv steam and products of com for heating and diluting. If antimonysulfide be employed, a limited quantity of air is used With the steam inplace of products of combustion.

What we claim is:

1. The process of preparing litharge in a state of fine sub-divisionfrom simple plumbiferous material free from sulfur and halogens whichcomprises dispersing lthe yraw material, distributing the same overheatedhot gas over the surfaces to -effect the volatilization of the rawmaterial, cooling the v volatilized material and eil'ecting the settlingof particles of largersize from the resultant fume andv subjecting thefume to the action of a precipitating means to form a finely dividedlitharge.

2. The process -of preparing finely divided materials frorn simpleplumbiferous materials :free from sul ur and halogens which comprisesdistributing the same as a film over heated refractory surfaces of largearea, passing a current of gases around the surfaces, thereby effectingthe volatilization of the raw material as a. fume suspended in thegases, and subjecting the fume to the action of a precipitating means toseparate the suspended material from the gas as a finely divided mass.

3. The process of preparing linelyl di.

vided .materials from metalliferous materials which comprisessub-dividing the Inaterial, passing the same through a shaft and over anextensive surface of refractory material inert with respect to thematerial and at a high temperature, flowing a current of hot gases overthe material to eiect its vo1a tilization and to form a fume suspendedin the gases, withdrawing the gaseous mass'and precipitating the fume.

.4. The process of preparing litharge fin a state of extremesub-division which comprises melting simple plumbiferous material freefrom sulfur and halogens, dis ersing the same over a-large area of heaterefractory material, passing a counter current of hot gases overthe-surfaces, volatilizing the plumbiferous material, cooling the sameto form a fume suspended in the gases, separating coarse particles bygravltal action, and precipitating the suspended fume from the gas toyield a finely dlvided litharge.

In testimony whereof, vwe aix our 'signatures.

. DR. Isa. Lui-)WIG SCHERTEL.

DR.' ING. WILLI LTY.

